As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
An information handling system may include a voltage regulator to provide a constant voltage level and a current to power the system. For example, a voltage regulator may receive an input voltage and produce an output current at a predetermined output voltage required by a load, i.e., the circuit element(s) for which it is providing power. Moreover, modern information handling systems may include components that maintain current requirements across a broad range from relatively high peak currents to very low stable currents. More particularly, voltage regulators may be required to maintain a high efficiency, or low power loss, over such ranges. In particular, a direct current to direct current (DC-DC) voltage regulator may include a controller, one or more drivers, and one or more power stages. Furthermore, a power stage may include one or more metal-oxide-semiconductor-field-effect-transistors (MOSFETs), which may be driven by the drivers.
Additionally, some voltage regulators may be capable of operating in multiple phases. To this end, the concept of a phase for a voltage regulator may typically refer to combining a driver and a power stage to form one phase. Thus, a multi-phase voltage regulator may include multiple instances of such combinations. Alternatively, a multi-phase voltage regulator may be thought of as a combination of single phase voltage regulators. For example, a multi-phase voltage regulator may include a plurality of single phase voltage regulators coupled in parallel to provide varying ranges of output current. During periods of high loads, the multi-phase voltage regulator may function with all phases in operation. In contrast, for lower loads, it may employ phase-shedding and operate with a reduced number of phases.
To manage power delivery and consumption by voltage regulators, power control systems in information handling systems often execute power management algorithms. For such power management algorithms to effectively manage power, accurate power measurements must be obtained. An inherent conflict in obtaining power measurements is that measurement circuitry itself may add power losses to a system.
In order to measure power consumption, both a voltage and a current must be obtained. As power consumed by loads (e.g., CPU) is first processed by a voltage regulator, the input power to a voltage regulator may equal the product of a voltage delivered to the voltage regulator and a current delivered to the voltage regulator. Existing approaches to measuring current associated with a voltage regulator include sensing a current in a component of a voltage regulator, such as a filter inductor of switching transistor integral to the voltage regulator, each of which has parasitic impedances. Current flowing through such components is linearly proportional to a voltage drop across such parasitic impedances. Thus by measuring a voltage across such components, a current associated with a voltage regulator may be obtained.
An advantage of using such components to obtain a current is that such impedances and their power losses are inherent to a voltage regulator, and thus such measurement approaches add little or no appreciable power consumption themselves. However, the impedances of these components may have large ranges of variation, and thus may result in unacceptable measurement error.
Accordingly, in order to obtain accurate real-time measurement of voltage regulator power, an additional impedance must often be inserted in series with the input power delivery path to a voltage regulator, and thus results in increased power loss. However, a disadvantage with such approach is that measurement accuracy and power dissipation of the impedance are in conflict with each other: to achieve greater measurement sensitivity, it may be desirable to use a larger impedance, but use of a larger impedance may lead to larger power loss.